224 FXUS66 KLOX 182117 AFDLOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 217 PM PDT Sun Jun 18 2017 .SYNOPSIS... A persistent and strong upper level ridge over the region will allow for very hot conditions across interior locations, including the Antelope Valley. Night through morning low clouds across coastal areas S of Point Conception are expected the next couple days. A modest cooling trend is expected by the end of the week. && .SHORT TERM...(TDY-WED) The marine stratus ran north this morning from the south coast, around Point Conception and arrived along the central coast up to Morro Bay where it is expected to remain through the evening. The overall pattern is similar to yesterday and afternoon temperatures will end up a couple of degrees warmer. The heat wave remains the main story. While mostly affecting areas further inland, downtown LA will be about five degrees above normal today and will warm even more through Tuesday before finally getting back down to normal on Saturday. Temperatures in the Antelope Valley will rise to around 110 during the peak of the event on Tuesday. Onshore flow which will help to keep coastal zones fairly mild once again today. The NE portion of the AV is expected to reach around 40 degrees Celsius. This should translate to highs reaching 105 to 108 across Lancaster/Palmdale and near 110 near Saddleback Butte. An Excessive Heat Warning went into effect this morning for the Antelope Valley through at least Wednesday. Expect highs to range between 107-112 Monday thru Wed. This may even be extended through Thursday. There will be triple digit heat in some of the lower mountain elevations. A heat advisory is in effect for the mountains, interior SLO county, and the Cuyama Valley through Wednesday evening as well. Upgrading the Advisory to a Warning for the LA County mountains on Monday morning, and for the San Luis Obispo County mountains and interior valleys on Tuesday morning. Expect high temps to range between 103-108 for these locations over the next few days. High temps across the Santa Clarita Valley will be reaching the lower 100s today. Highs in the San Fernando and San Gabriel Valleys as well as the Ventura County Valleys will reach the mid to upper 90s but a bit cooler nearer the coast to the lower 90s. There will be areas of patchy smoke today around Santa Clarita Valley and Antelope Valley from the fire burning near Castaic Lake. Models continue to show an eddy circulations across the LA/VTU coastal waters and should expect some kind of stratus to redevelop tonight into Monday and possibly again Monday night into Tue morning but remain limited to coastal areas. The heat will really be on Mon/Tue across the interior areas with a few more degrees of warming for the valleys, mountains, and the interior areas as well as the Antelope Valley where as already mentioned highs reaching 110 degrees will be likely each day. Wednesday will remain hot away from the coast, but temperatures will begin to fall with slight height falls, but they will remain above 590 DM. .LONG TERM...(THU-SUN) There should be a few degrees of relief starting Thursday for inland areas, but still quite hot across the AV. Expect 3-5 degrees of cooling across valleys with this modest cooling trend continuing through Sunday. Highs will still remain above normal for most areas away from the immediate coast. Some night through morning low clouds are expected along the LA/VTU coast and possibly the SBA South Coast, and some patchy low clouds and fog could affect the portions of the Central Coast as well. && .AVIATION...18/12z At 08Z at KLAX... the inversion was around 700 ft. The top of the inversion was around 2600 ft with a temperature of about 24 degrees Celsius. Overall... Moderate confidence in the current coastal TAFs and higher confidence in the inland TAFs. Through 18z VLIFR/LIFR conditions at coastal sites south of Point Conception and at KSMX will waft in and out during this period due to the influence of the Catalina eddy. Through 18z there is a twenty percent chance of LIFR/IFR conditions at KSBP... KVNY... and KBUR. Similar conditions are likely to return after 19/07z. Otherwise and elsewhere VFR conditions will prevail through the forecast period. KLAX... Moderate confidence in the current TAF. Through 18z VLIFR/LIFR conditions will waft in and out due to the influence of the Catalina eddy. Otherwise VFR conditions will prevail. Similar conditions are likely to return after 19/09z. No east winds greater than 7 knots are expected. KBUR... Moderate to high confidence in the current TAF. Through 18z there is a twenty percent chance of LIFR/IFR conditions. Otherwise VFR conditions will prevail through the forecast period. && .MARINE...18/200 PM... Low clouds and local fog continues to cover sections of inner waters from Los Angeles to San Luis Obispo County this afternoon. The central coast is the most difficult forecast but currently looks more entrenched than anywhere else. Low confidence about amount of fog in this area, but do expect widespread visibilities to one mile or less across southern coastal waters late tonight and Monday morning. Winds are generally light through Monday. There will be an increase in south swell mixing with westerly swell Tuesday through Thursday. For the outer waters, areas of fog with visibilities less than one mile possible tonight through Monday. West to northwest swell builds to 8-10 ft Tuesday through Thursday and expect gusty northwest winds getting into SCA levels starting Monday night for the northwest sector of zone 676 and zones 670-673. For the inner waters, winds and seas will remain below SCA levels through Thursday. && .BEACHES...18/900 am. A mixture of south and west swell and building high tides will bring increasing rip current risk to the Ventura and Los Angeles County coasts through the week. The peak days will be Tuesday through Thursday when larger surf heights will lead to strong and dangerous rip currents at the beaches and a significant risk for ocean drowning. This risk will be compounded by the extended period of very hot temperatures over the inland areas next week which will lead to more people at the beaches and in the water than usual. This is a serious risk. Beaches with active lifeguard patrols are typically the safest, however, beachgoers should always ask lifeguards about known rip current areas before going into the water. Stay alert to the ocean conditions and updates about this building rip current risk during the week. && .FIRE WEATHER...18/950 AM. High pressure aloft continues to build over Socal through Tuesday bringing 2-4 degrees of warming Sunday through Tuesday away from the immediate coast. The combination of increasing temperatures and shrinking marine layer will cause humidities to falling up to 5 percent interior areas and up to 15 percent interior coastal areas into the valleys by Tuesday. This will result in triple digit heat for interior areas including many valley locations by Tuesday with minimum humidities of 10 to 25 percent range away from the coast except for single digits for the Antelope Valley and higher elevations possibly including the Carrizo Plain into the Cuyama Valley. Winds through Wednesday be on the lighter side except for diurnally driven onshore winds for interior areas with gusts generally up to around 30 mph except for downsloping areas like the foothills of the Antelope Valley with gusts up to around 40 mph. Onshore winds will likely increase 5 to 10 mph Thursday. The onshore winds will likely transport smoke from the Lake Fire through the mountains and possibly reaching western portions of the Antelope Valley each afternoon and evening while the fire is active. The combination of increasing temperatures and lowering humidities will bring continued elevated fire weather conditions for interior areas through Thursday with brief critical conditions possible in wind prone areas such as the 14 corridor into the foothills of the Antelope Valley early next week. Additionally, the hot and unstable weather conditions with generally light winds could lead to plume dominated fire potential, especially in the foothills and mountains, including the Lake Fire. Gusty and erratic winds are possible near the Lake Fire if it becomes plume dominated. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory in effect until 11 AM PDT Tuesday for zones 37-51. (See LAXNPWLOX). Excessive Heat Warning in effect from 11 AM Tuesday to 9 PM PDT Wednesday for zones 37-51. (See LAXNPWLOX). Heat Advisory in effect until 9 PM PDT Wednesday for zones 38-52-53-88. (See LAXNPWLOX). Heat Advisory in effect from 11 AM Tuesday to 9 PM PDT Wednesday for zone 41. (See LAXNPWLOX). Heat Advisory in effect from 11 AM Monday to 9 PM PDT Wednesday for zones 44>46-547. (See LAXNPWLOX). Heat Advisory in effect until 11 AM PDT Monday for zone 54. (See LAXNPWLOX). Excessive Heat Warning in effect from 11 AM Monday to 9 PM PDT Wednesday for zone 54. (See LAXNPWLOX). Excessive Heat Warning in effect until 9 PM PDT Wednesday for zone 59. (See LAXNPWLOX). PZ...NONE. && .HAZARD POTENTIAL OUTLOOK...(WED-SUN) Hot temperatures and potential heat impacts are likely for inland and mountain areas and across the Antelope Valley. Impacts are expected to be greatest Wednesday, especially over the Antelope Valley where high temperatures Wednesday are expected to be around 110 degrees. Temperatures will remain above normal until at least Saturday. && $$ PUBLIC...jld AVIATION...Kj MARINE...EB BEACHES...EB FIRE...Munroe SYNOPSIS...B weather.gov/losangeles